ref: 7c3c214956595eb6e42d2b791feb8366835b689c
dir: /src/flanger.c/
/*
* August 24, 1998
* Copyright (C) 1998 Juergen Mueller And Sundry Contributors
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Juergen Mueller And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
/*
* Flanger effect.
*
* Flow diagram scheme:
*
* * gain-in ___
* ibuff -----+--------------------------------------------->| |
* | _______ | |
* | | | * decay | |
* +---->| delay |------------------------------->| + |
* |_______| | |
* /|\ | |
* | |___|
* | |
* +---------------+ +------------------+ | * gain-out
* | Delay control |<-----| modulation speed | |
* +---------------+ +------------------+ +----->obuff
*
*
* The delay is controled by a sine or triangle modulation.
*
* Usage:
* flanger gain-in gain-out delay decay speed [ -s | -t ]
*
* Where:
* gain-in, decay : 0.0 ... 1.0 volume
* gain-out : 0.0 ... volume
* delay : 0.0 ... 5.0 msec
* speed : 0.1 ... 2.0 Hz modulation
* -s : modulation by sine (default)
* -t : modulation by triangle
*
* Note:
* when decay is close to 1.0, the samples may begin clipping or the output
* can saturate!
*
* Hint:
* 1 / out-gain > gain-in * ( 1 + decay )
*
*/
/*
* Sound Tools flanger effect file.
*/
#include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */
#include <math.h>
#include <string.h>
#include "st.h"
#define MOD_SINE 0
#define MOD_TRIANGLE 1
/* Private data for SKEL file */
typedef struct flangerstuff {
int modulation;
int counter;
int phase;
double *flangerbuf;
float in_gain, out_gain;
float delay, decay;
float speed;
long length;
int *lookup_tab;
long maxsamples, fade_out;
} *flanger_t;
/* Private data for SKEL file */
LONG flanger_clip24(l)
LONG l;
{
if (l >= ((LONG)1 << 24))
return ((LONG)1 << 24) - 1;
else if (l <= -((LONG)1 << 24))
return -((LONG)1 << 24) + 1;
else
return l;
}
/* This was very painful. We need a sine library. */
void flanger_sine(buf, len, depth)
int *buf;
long len;
long depth;
{
long i;
double val;
for (i = 0; i < len; i++) {
val = sin((double)i/(double)len * 2.0 * M_PI);
buf[i] = (int) ((1.0 + val) * depth / 2.0);
}
}
void flanger_triangle(buf, len, depth)
int *buf;
long len;
long depth;
{
long i;
double val;
for (i = 0; i < len / 2; i++) {
val = i * 2.0 / len;
buf[i] = (int) (val * depth);
}
for (i = len / 2; i < len ; i++) {
val = (len - i) * 2.0 / len;
buf[i] = (int) (val * depth);
}
}
/*
* Process options
*/
void flanger_getopts(effp, n, argv)
eff_t effp;
int n;
char **argv;
{
flanger_t flanger = (flanger_t) effp->priv;
if (!((n == 5) || (n == 6)))
fail("Usage: flanger gain-in gain-out delay decay speed [ -s | -t ]");
sscanf(argv[0], "%f", &flanger->in_gain);
sscanf(argv[1], "%f", &flanger->out_gain);
sscanf(argv[2], "%f", &flanger->delay);
sscanf(argv[3], "%f", &flanger->decay);
sscanf(argv[4], "%f", &flanger->speed);
flanger->modulation = MOD_SINE;
if ( n == 6 ) {
if ( !strcmp(argv[5], "-s"))
flanger->modulation = MOD_SINE;
else if ( ! strcmp(argv[5], "-t"))
flanger->modulation = MOD_TRIANGLE;
else
fail("Usage: flanger gain-in gain-out delay decay speed [ -s | -t ]");
}
}
/*
* Prepare for processing.
*/
void flanger_start(effp)
eff_t effp;
{
flanger_t flanger = (flanger_t) effp->priv;
int i;
flanger->maxsamples = flanger->delay * effp->ininfo.rate / 1000.0;
if ( flanger->in_gain < 0.0 )
fail("flanger: gain-in must be positive!\n");
if ( flanger->in_gain > 1.0 )
fail("flanger: gain-in must be less than 1.0!\n");
if ( flanger->out_gain < 0.0 )
fail("flanger: gain-out must be positive!\n");
if ( flanger->delay < 0.0 )
fail("flanger: delay must be positive!\n");
if ( flanger->delay > 5.0 )
fail("flanger: delay must be less than 5.0 msec!\n");
if ( flanger->speed < 0.1 )
fail("flanger: speed must be more than 0.1 Hz!\n");
if ( flanger->speed > 2.0 )
fail("flanger: speed must be less than 2.0 Hz!\n");
if ( flanger->decay < 0.0 )
fail("flanger: decay must be positive!\n" );
if ( flanger->decay > 1.0 )
fail("flanger: decay must be less that 1.0!\n" );
/* Be nice and check the hint with warning, if... */
if ( flanger->in_gain * ( 1.0 + flanger->decay ) > 1.0 / flanger->out_gain )
warn("flanger: warning >>> gain-out can cause saturation or clipping of output <<<");
flanger->length = effp->ininfo.rate / flanger->speed;
if (! (flanger->flangerbuf =
(double *) malloc(sizeof (double) * flanger->maxsamples)))
fail("flanger: Cannot malloc %d bytes!\n",
sizeof(double) * flanger->maxsamples);
for ( i = 0; i < flanger->maxsamples; i++ )
flanger->flangerbuf[i] = 0.0;
if (! (flanger->lookup_tab =
(int *) malloc(sizeof (int) * flanger->length)))
fail("flanger: Cannot malloc %d bytes!\n",
sizeof(int) * flanger->length);
if ( flanger->modulation == MOD_SINE )
flanger_sine(flanger->lookup_tab, flanger->length,
flanger->maxsamples - 1);
else
flanger_triangle(flanger->lookup_tab, flanger->length,
flanger->maxsamples - 1);
flanger->counter = 0;
flanger->phase = 0;
flanger->fade_out = flanger->maxsamples;
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
void flanger_flow(effp, ibuf, obuf, isamp, osamp)
eff_t effp;
LONG *ibuf, *obuf;
int *isamp, *osamp;
{
flanger_t flanger = (flanger_t) effp->priv;
int len, done;
double d_in, d_out;
LONG out;
len = ((*isamp > *osamp) ? *osamp : *isamp);
for(done = 0; done < len; done++) {
/* Store delays as 24-bit signed longs */
d_in = (double) *ibuf++ / 256;
/* Compute output first */
d_out = d_in * flanger->in_gain;
d_out += flanger->flangerbuf[(flanger->maxsamples +
flanger->counter - flanger->lookup_tab[flanger->phase]) %
flanger->maxsamples] * flanger->decay;
/* Adjust the output volume and size to 24 bit */
d_out = d_out * flanger->out_gain;
out = flanger_clip24((LONG) d_out);
*obuf++ = out * 256;
/* Mix decay of delay and input */
flanger->flangerbuf[flanger->counter] = d_in;
flanger->counter =
( flanger->counter + 1 ) % flanger->maxsamples;
flanger->phase = ( flanger->phase + 1 ) % flanger->length;
}
/* processed all samples */
}
/*
* Drain out reverb lines.
*/
void flanger_drain(effp, obuf, osamp)
eff_t effp;
LONG *obuf;
int *osamp;
{
flanger_t flanger = (flanger_t) effp->priv;
int done;
double d_in, d_out;
LONG out;
done = 0;
while ( ( done < *osamp ) && ( done < flanger->fade_out ) ) {
d_in = 0;
d_out = 0;
/* Compute output first */
d_out += flanger->flangerbuf[(flanger->maxsamples +
flanger->counter - flanger->lookup_tab[flanger->phase]) %
flanger->maxsamples] * flanger->decay;
/* Adjust the output volume and size to 24 bit */
d_out = d_out * flanger->out_gain;
out = flanger_clip24((LONG) d_out);
*obuf++ = out * 256;
/* Mix decay of delay and input */
flanger->flangerbuf[flanger->counter] = d_in;
flanger->counter =
( flanger->counter + 1 ) % flanger->maxsamples;
flanger->phase = ( flanger->phase + 1 ) % flanger->length;
done++;
flanger->fade_out--;
}
/* samples playd, it remains */
*osamp = done;
}
/*
* Clean up flanger effect.
*/
void flanger_stop(effp)
eff_t effp;
{
flanger_t flanger = (flanger_t) effp->priv;
free((char *) flanger->flangerbuf);
flanger->flangerbuf = (double *) -1; /* guaranteed core dump */
free((char *) flanger->lookup_tab);
flanger->lookup_tab = (int *) -1; /* guaranteed core dump */
}